So I came across this guys diagram and instructions to build an arc welder from an alternator, I've never attempted to build a welder, so had a few questions I was hoping someone a bit more knowledgeable than I could help me out with, first off does this look like it's going to work at all? http://diy-welder.com/weldernator.shtml
Second they have me a bit confused about the sizing of the capacitor; and how would you connect the capacitor?
I have seen that before and it worked relatively well. Its been a while and do not recall the details but i thought they might find a better alt considering zo many newer ones are really powerful. I only saw, never used, not sure how long it might last etc.
At one time it might have been more practical but now a lunchbox on a gen set would be my scheme for utility and allow for use of line power at both voltages. Its not a bad thing, just a longer way around.
This will help you a lot: https://www.otherpower.com/images/sc...or_Secrets.pdf
I think it comes down to a few things: The alternator amp rating which will correlate to the thickness of the windings and how much current they can handle, and the rating of the diodes. Exceed either one of those and your experiment will damage something in the alternator. If you are going for constant current welding (stick/TIG) you will want a fairly large inductor (aka reactor) in series with the output. Inductors essentially store current and keep the current more or less constant. A small cap is used to smooth out the ripple, which is probably not an issue with a 3 phase alternator. A larger cap or series of caps will convert the unit to more of a constant voltage power supply, since caps store voltage.
Miller Multimatic 255